This article examines Catholic architecture in Ireland prior to the passage of An act for the relief of His Majesty's Roman Catholic subjects (10 Geo IV, c. 7), popularly known as the Act of Emancipation, in 1829. It focuses on one case study building — the chapel, now church, of St John the Baptist in Cashel, County Tipperary. Bringing together a range of documentary and visual sources, this building is analysed according to its site, its specific architectural stylistic features, and in relation to the social and liturgical contexts for its development. The article contributes to the ongoing reassessment of the impact of the penal laws and the varied experiences of Catholics through the late eighteenth-century period of relief and reform, through its spatial, formal and contextual close reading of one hitherto overlooked building. In doing so, it deepens understanding of how architecture was used as a statement of civic identity and political intention by Catholics of status and means. It also contributes to contemporary understandings of regional classicism and to the specific meaning of ecclesiastical architectural style in late-eighteenth-century Ireland across denominations. Finally, this article considers the treatment and ‘strategic forgetting’ of this period of pre-1829 Catholic building activity during the era of grand architectural expansion at the end of the nineteenth century.